1. Field of the Invention
The present invention relates to a bearing lubricating apparatus for a rotary machine wherein a rotary shaft is rotatably supported within a casing via a bearing, an oil reservoir is disposed below a bearing chamber in which the bearing is contained, and lubricating oil picked up by an oil pick-up member mounted on an end portion of the rotary shaft and immersed into the lubricating oil in the oil reservoir is supplied to the bearing.
2. Prior Arts
As is well-known, various arts for supplying lubricating oil to bearings of rotary machines are already known. For example, an art in which lubricating oil is picked up by an oil disc or an oil gear and the picked-up oil is dropped down along an inner surface of a casing while the oil is supplied to a bearing, or an art in which positive jet lubrication is effected by using a pump as disclosed in JP-A-58-193997 (Patent Public Disclosure No. 193997/83) are known. However, the former art is limited to applications wherein a rotational speed of a rotary member is relatively slow and provides a small amount of lubricating oil, whereas, the latter art inevitably makes the construction complicated and bulky.
To eliminate the above drawbacks, the Applicant has proposed a technique in which an adequate amount of lubricating oil can easily be supplied to a bearing by the aid of a rotational force of a rotary shaft, as disclosed in JP-A-5-340371 (Patent Public Disclosure No. 340371/93).
To properly understand the present invention, the technique proposed in the above JP-A-5-340371 is shown in FIG. 5 wherein a rotor shaft 42 is rotatably supported within a casing 44 via a rolling bearing 35, an oil reservoir 46 is disposed below a bearing chamber in which the rolling bearing 35 is contained, and lubricating oil is picked up by an oil disc 34 mounted on an end portion of the rotor shaft 42 and immersed into the lubricating oil.
In an inner surface of a cover 41 attached to an end of the casing 44, there is provided a guide groove G for collecting the lubricating oil picked up by the oil disc 34 and flowing down along the inner surface, and a guide plate 32 is disposed at one side of the guide groove G. A suction nozzle 33 for sucking the lubricating oil collected into the guide groove G protrudes into the guide groove. A lubricating passage 37 for guiding the lubricating oil sucked by the suction nozzle 33 is formed in the rotor shaft 42. Oil supply nozzles 38 communicated with the lubricating passage 37 serve to effect a pumping action as the rotor shaft 42 is rotated.
When the rotor shaft 42 is rotated, the lubricating oil sucked from the guide groove G through the suction nozzle 33 by the pumping action generated by a centrifugal force regarding the oil supply nozzles 38 is supplied to the rolling bearing 35 through the lubricating passage 37. By passing the lubricating oil through the lubricating passage 37 formed in the rotor shaft 42 in this way, the rotor shaft 42 is cooled. Since a supply amount of the lubricating oil is determined by a rotational speed of the rotor shaft 42 and diameters of the oil supply nozzles 38 and the suction nozzle 33, the optimum supply amount of the lubricating oil can be obtained by changing the diameters of the nozzles. Incidentally, in FIG. 5, by providing a jacket 43 formed in the cover 41, the lubricating oil in the oil reservoir 46 and the lubricating oil flowing downwardly along the inner surface can be cooled easily. Further, when a bent portion is formed on an end portion of the oil disc 34, a sufficient amount of oil can be picked up. Incidentally, the reference numeral 39 denotes a discharge port of a vacuum pump; 40 denotes a timing gear mounted on the end portion of the rotor shaft 42; 45 denotes a cooling jacket formed in the casing; and 56 denotes a shaft seal.
While the above-mentioned technique itself is effective, since the oil flow is weak in the inner side of the lubricating passage 37, this technique cannot be adopted to applications where a shaft is heated to a high temperature because a bearing cannot be cooled sufficiently.